CN102252779B - Flue gas energy balance-based method for optimized measurement of flue gas temperature at furnace outlet - Google Patents

Abstract

The invention, which belongs to the field of information processing technology, relates to a method for optimized measurement of a flue gas temperature at a furnace outlet, wherein the method is based on energy balance of flue gas. According to the invention, on the basis of actual operation data related to a model parameter in a set and according to energy balance between combustion and radiation of a furnace, energy balance between a flue gas side and a working medium side of a superheater, energy balance between a flue gas side and a working medium side of a reheater and energy balance of tail flue gas, a flue gas temperature of the furnace is optimizingly measured at positive and negative directions of the flue gas side and a final result of the flue gas temperature is calculated compoundedly on the basis of results that are obtained by respected measurements. In an actual operation, a parameter in the method can be corrected according to an operation state of the set; therefore, the method provided in the invention has good universality and robustness; moreover, a requirement for an actual on-site monitoring system is low. The method provided in the invention is suitable for detection of an operation state and optimization of a combustion state of a thermal power generation system.

Description

Furnace outlet gas temperature based on the gas energy balance is optimized measuring method

Technical field

What the present invention relates to is a kind of method of technical field of information processing, specifically is that a kind of furnace outlet gas temperature based on the gas energy balance is optimized measuring method.

Background technology

Boiler is as the important component part of fired power generating unit, and along with the increase of unit capacity, its structure becomes increasingly complex, and the parameter of required detection and control is also more and more, has brought new problem to its control and optimization.Burner hearth is as entering the combustion space of steam generator system fuel and the main heating surface of steam generator system radiant heat transfer, and it has, and volume is big, the complicated characteristics of the many and inner operating mode of input and output amount.Burner hearth heating power calculates as the important component part in the boiler heating power calculating, and its main furnace outlet gas temperature as a result is significant to modeling, heating power calculating and the efficiency evaluation of whole boiler.

Rise the seventies in 20th century, more domestic research institutions utilize various computational languages to develop many heating power computing systems with certain practicality, heating power computing system as Zhejiang University in 1998 and Hangzhou Boiler Factory's cooperative development is applied in Hangzhou Boiler Factory, producer of Taiyuan, Boiler Factory; The heating power computing system at combustion machine waste heat boiler that Zhejiang University in 2002 and Hitachi boiler factory, east, Jiaxing develop jointly.Because being subjected to the influence of development technique, method, language and computation model self structure complexity and the big factor of dispersion, aspect software development technique, there are versatility, stability, expandability, maintainable difference and the low problem of computational accuracy.Also present certain region because distribution of coal sorts difference, China's boiler are used to distribute, there is certain limitation in present boiler heating power computing system to the selection of coal.

Through existing literature search is found, " heating power of furnace of power-plant boilers calculates and emulation " on " Agricultural University of the Inner Mongol's journal " is on the basis of the present situation of analyzing boiler heating power calculating and heating power software for calculation, heating power calculating at boiler furnace is concluded, is summed up and simplifies, and has proposed relevant heating power calculation procedure.This method possess versatility good, calculate simple characteristics.But this method lacks field data checking effectively or several different methods result comparison owing to only adopt the directed energy balanced algorithm, and cogency is not enough.

The Zhou Huaichun of coal combustion National Key Laboratory of the Central China University of Science and Technology proposes a kind of boiler and furnace temp is field visualized and boiler and furnace temp is field visualized and the burning monitoring technique, detects principle and technology detects two-dimensional/three-dimensional temperature in the large-sized boiler stove based on heat radiation image treatment temperature.This method possesses the high characteristics of accuracy of detection, and can detect all sidedly three-dimensional temperature field in the stove, but the heat radiation measuring instrument that its correlation technique is special because needs add has proposed higher requirement to the detection system of boiler furnace, temporarily can't promote on a large scale.

Summary of the invention

The present invention is directed to the prior art above shortcomings, provide a kind of furnace outlet gas temperature based on the gas energy balance to optimize measuring method, by actual operating data relevant with model parameter in the unit, according to burner hearth burning and emittance balance, superheater fume side and working medium side energy equilibrium, reheater fume side and working medium side energy equilibrium and exit gas energy balance, from the positive and negative both direction of fume side burner hearth cigarette temperature has been carried out optimizing measurement, and the final cigarette temperature of compound calculating result on the basis of difference measurement result.Can be according to unit operation situation modification method parameter in actual motion, make this inventive method have good versatility and robustness, and lower to the requirement of actual field monitoring system, be applicable to the operation conditions detection of thermal power generation system and the optimization of combustion position.

The present invention is achieved by the following technical solutions, the present invention includes following steps:

Step 1: setting comprises the heat interchanging area of furnace volume, heat interchanging area and heat interchanger at different levels, boiler furnace and the flue characteristic of metal quality, by the OPC communications protocol, set up the OPC client and send request of data to the opc server end that DCS carries, carry out real-time sampling and obtain the boiler operatiopn data, data are carried out 5 smoothing processing.

The time interval of described sampling is 5 seconds;

Step 2: set up science computing platform and man-machine interactive platform on the control systems engineering (CSE) teacher station at the scene, namely utilize Matlab to set up data processing platform (DPP), the OPC client that carries based on Matlab is used for realizing that data receive and handle.

Step 3: burning exothermic equilibrium and water-cooling wall radiation heat transfer balance based on boiler furnace calculate furnace outlet gas temperature T ₁Based on exit gas energy, reheater energy equilibrium and the superheater energy equilibrium of boiler flue, utilize flue gas physical parameter storehouse, calculate furnace outlet gas temperature T ₂, concrete steps comprise:

A) utilize forward fire coal heat release and heat transfer balance in burner hearth, calculate the furnace outlet temperature T ₁

B) utilize the heat production balance of reverse flue gas in heat interchanger at different levels, utilize tail gas energy to add that heat interchanger at different levels transmit heat Calculation and go out the furnace outlet gas energy, and utilize the anti-furnace outlet gas temperature T that pushes away of flue gas rerum natura ₂

Step 4: obtain furnace outlet gas temperature T according to forward combustion exothermic equilibrium and reverse superheater reheater heat interchange EQUILIBRIUM CALCULATION FOR PROCESS ₁With T ₂, the mode of employing linear superposition, i.e. T=a * T ₁+ b * T ₂Calculate final burner hearth cigarette temperature result, wherein coefficient a gets 0.3, and coefficient b gets 0.7.

Step 5: the burner hearth coefficient of heat transfer etc. was respectively organized parameter during the change correcting method that takes place as time passes according to natural fuel characteristic and burner hearth, flue, heat interchanger characteristic was carried out, and namely carry out parameter and roll and upgrade optimizing measuring method, specifically:

A) utilize every day up-to-date ature of coal on-line analysis value that flue gas physical parameter storehouse is upgraded;

B) after each overhaul various parameters such as the burner hearth coefficient of heat transfer are reset.

Compared with prior art, the present invention possesses following three advantages: the one, and need not adding hardware and drop into, only need to utilize data that existing detection system obtains and the analysis data of part thermal power generation system, avoided newly-increased investment and technological transformation; The 2nd, according to the thermal power generation system of different model and scale, only need to relate to by retouch the parameter of boiler structure, need not model result is made a new start; The 3rd, adopted two kinds of different fume side energy equilibrium, run through whole exhaust gases passes, cover multiple uncertainty, and can carry out mutual verification.Result of the present invention more helps judging and further optimization boiler overall operation situation.

Description of drawings

Fig. 1 is flue gas rerum natura curve map.

Fig. 2 is furnace outlet gas temperature final calculation result and load data contrast figure.

Embodiment

Below embodiments of the invention are elaborated, present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Boiler in the present embodiment meets the following conditions: this boiler is load 300MV, subcritical, Natural Circulation, resuperheat, two arch list burner hearth, " W " flame combustion mode, dry ash extraction, the coal-fired drum boiler of all steel frame suspension type.

Present embodiment may further comprise the steps:

Step 1: boiler furnace and flue characteristic are set, and set coal-fired composition and net calorific value, characterisitic parameter such as table 1:

Table 1 boiler physical characteristics parameter

This boiler DCS control system carries the OPC service end, can read a pot service data in real time by the OPC client in this optimization measuring method implementation, and the sampling period is 5 seconds.Calculate the flue gas physical property, according to the data that the real-time coal analysis instrument at scene provides, calculate every characteristic of the product behind the 1Kg fired coal combustion, and set up flue gas physical data storehouse.

And the enthalpy of flue gas can be according to O ₂, CO ₂, H ₂O, N ₂The volume composition of gas and flue-gas temperature utilize the enthalpy property calculation of various composition gases to obtain, typical mean composition flue gas (r _CO2=0.13, r _H2O=0.11, r _N2=0.76), its specific heat of combustion as shown in Figure 1; The enthalpy of working-medium water obtains according to the IAPWS-IF97 formula.

Step 2: set up science computing platform and human-computer interaction interface the engineer station.

Step 3: can get the furnace outlet temperature and enter lumped parameter model between the burner hearth Coal-fired capacity according to furnace heat transfer similarity theory computing method:

${\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">T</figure-callout>}}_1={T^{\&prime;\&prime;}}_1-273=\frac{T_a}{M{\left(\frac{{\mathrm{\&sigma;}}_0{a}_1\mathrm{\&psi;}{F}_1{T}_a^3}{\mathrm{\&phi;}{B}_j\stackrel{\&OverBar;}{V_{C_p}}}\right)}^{0.6}+1}$

Wherein: B _jBe calculated fuel consumption, be measured value; σ ₀Be Boltzmann's constant; F ₁For burner hearth heat exchange wall area, be 2900m ²

For considering the hot coefficient of guarantor of burner hearth radiation loss, be 0.85; I " ₁Enthalpy Q for products of combustion on the furnace outlet cross section ₁For the equivalent fuel amount is sent into net heat in the burner hearth; V _CpBe the mean specific heat of products of combustion, look into flue gas physical parameter Ku Kede; T _aBeing the absolute temperature of combustion of products of combustion, is 2400 ℃; T " ₁Be flue gas temperature of hearth outlet; Ψ is that the effective heat absorption coefficient of water-cooling wall is 0.45, a ₁Being the burner hearth blackness, is 0.63.

According to follow-up gas energy balance, furnace outlet high-temperature flue gas energy satisfies following formula:

The energy that reduces in high-temperature flue gas energy=flue gas heat interchange+flue tail gas energy

The energy phase of working medium increase in the energy that reduces when better this hypothesis can think that flue gas passes through heat interchanger based on the thermal insulation of flue and the heat interchanger.Be that the fume side energy equilibrium can be rewritten as:

Energy+flue tail gas energy that working medium increases in high-temperature flue gas energy=heat interchanger

By the studying coal-fired boiler structure of institute as can be known heat interchanger mainly be divided into superheater and reheater, thereby oppositely derive to calculate and need main consider superheater and heat interchanger heat exchange amount and exit gas energy.

(a) superheater heat transfer model

Can get according to working medium mass balance in the superheater:

$\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">M</figure-callout>}}_1}{\mathrm{\&Delta;t}}=D_{\mathrm{in}1}-D_{\mathrm{out}1}$

ΔM ₁＝M ₁(k)-M ₁(k-1)＝[ρ ₁(k)-ρ ₁(k-1)]V ₁

$D_{\mathrm{in}1}=\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">M</figure-callout>}}_1}{\mathrm{\&Delta;t}}+D_{\mathrm{out}1}$

In the formula: k is current time, and k-1 is previous moment, D _In1Be drum outlet saturated vapour flow, i.e. superheater system input quality, D _Out1Be high pressure cylinder entrance superheat steam flow, i.e. superheater system output quality, M ₁Be working medium gross mass in the superheater system, V ₁Be superheater volume, p ₁Average density for working medium in the superheater system.

Can get according to working medium energy equilibrium in the superheater:

$\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}{\mathrm{\&Delta;t}}=Q_{\mathrm{in}1}+\mathrm{\&Delta;}{Q}_{\mathrm{gas}1}-Q_{\mathrm{out}1}=D_{\mathrm{in}1}{H}_{\mathrm{in}1}+\mathrm{\&Delta;}{Q}_{\mathrm{gas}1}-D_{\mathrm{out}1}{H}_{\mathrm{out}1}$

ΔE ₁＝E ₁(k)-E ₁(k-1)＝[ρ ₁(k)H ₁(k)-ρ ₁(k)H ₁(k)]V+c _metal1M _metal1ΔT _metal1

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="Q\; gas"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">Q</figure-callout>}}_{\mathrm{gas}}=\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">E</figure-callout>}}_1}{\mathrm{\&Delta;t}}+Q_{\mathrm{out}1}-Q_{\mathrm{in}1}$

In the formula: k is current time, and k-1 is previous moment, Q _In1Be the saturated vapour energy, i.e. superheater system input energy, Q _Out1Be the superheated vapor energy, i.e. superheater system output energy, E ₁Be working medium gross energy in the superheater, H _In1And H _Out1Be respectively saturated vapour enthalpy and superheated vapor enthalpy, c _Metal1, M _Metal1With Δ T _Metal1Be specific heat, quality and the temperature fluctuation of superheater pipeline metallic walls, Δ Q _Gas1For flue gas passes to the energy of working medium by superheater, i.e. the energy that in the superheater heat interchange, reduces of flue gas.

(b) reheater heat transfer model

Can get according to working medium energy equilibrium in the reheater:

$\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">M</figure-callout>}}_2}{\mathrm{\&Delta;t}}=D_{\mathrm{in}2}-D_{\mathrm{out}2}$

D _in2＝D _main-D _s1-D _s2

ΔM ₂＝M ₂(k)-M ₂(k-1)＝[ρ ₂(k)-ρ ₂(k-1)]V ₂

$D_{\mathrm{out}2}=D_{\mathrm{in}2}-\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">M</figure-callout>}}_2}{\mathrm{\&Delta;t}}$

In the formula: k is current time, and k-1 is previous moment, D _In2For high pressure cylinder exports cold reheated steam flow, i.e. reheater system input quality, D _Out2Be intermediate pressure cylinder entrance reheat heat steam flow, i.e. reheater system output quality, D _S1, D _S2Be respectively high pressure cylinder and send into the steam flow that height adds 1# and Gao Jia 2#, D _MainBe main steam flow, with D in the formula (5) _Out1Phase, M ₂Be working medium gross mass in the reheater system, V ₂Be reheater volume, ρ ₂Average density for working medium in the superheater system.

Can get according to the reheater energy equilibrium:

$\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}{\mathrm{\&Delta;t}}=Q_{\mathrm{in}2}+\mathrm{\&Delta;}{Q}_{\mathrm{gas}2}-Q_{\mathrm{out}2}=D_{\mathrm{in}2}{H}_{\mathrm{in}2}+\mathrm{\&Delta;}{Q}_{\mathrm{gas}2}-D_{\mathrm{out}2}{H}_{\mathrm{out}2}$

ΔE ₂＝E ₂(k)-E ₂(k-1)＝[ρ ₂(k)H ₂(k)-ρ ₂(k)H ₂(k)]V+c _metal2M _metal2ΔT _metal2

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="Q\; gas"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">Q</figure-callout>}}_{\mathrm{gas}}=\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000058005870000012.png"\; state="\{\{state\}\}">E</figure-callout>}}_2}{\mathrm{\&Delta;t}}+Q_{\mathrm{out}2}-Q_{\mathrm{in}2}$

In the formula: k is current time, and k-1 is previous moment, Q _In2Be cold reheated steam energy, i.e. reheater system input energy, Q _Out2Be the reheat heat steam energy, i.e. reheater system output energy, E ₂Be working medium gross energy in the reheater, H _In2And H _Out2Be respectively cold reheated steam enthalpy and reheat heat steam enthalpy, c _Metal2, M _Metal2With Δ T _Metal2Be superheater pipeline gold Δ Q _Gas2For flue gas passes to the energy of working medium by reheater, i.e. the energy that in the reheater heat interchange, reduces of flue gas.

(c) exit gas energy balance model

Flue gas is the product behind fuel and the oxygen generation chemical reaction.The principal ingredient of flue gas has nitrogen, carbon dioxide, and oxygen and water vapor also have a spot of hydrogen, methane and other oxides (as sulphuric dioxide, nitrogen dioxide, carbon monoxide).

The tail gas energy computing method adopt the method based on the smoke components ratio.Computing method are as follows:

Q _gas3＝K(Q _py-Q _lf)

In the formula: K is the imperfect combustion modified value of coal-fired solid, Q _PyBe smoke evacuation energy, Q _LfBe the cold air energy.

Thereby the energy method computations of furnace outlet flue gas is:

Q＝Q _gas1+Q _gas2+Q _gas3

Can be by the anti-flue gas temperature of hearth outlet T that pushes away of flue gas physical parameter table based on the furnace outlet flue gas ability ₂

Step 4: according to obtaining furnace outlet gas temperature T based on two kinds of soft measurement means ₁With T ₂, the mode of employing certain proportion linear superposition, i.e. T=a * T ₁+ b * T ₂Calculate final burner hearth cigarette temperature result.

In the present embodiment, set a=0.3, b=0.7 calculates final furnace outlet temperature T, and it is worth between 950～1050 ℃.The measuring and calculating value in one sky as shown in Figure 2.

Step 5: in optimizing the measuring method implementation, based on the coal assay value real-time update ature of coal situation of Fourth Shift's every day of chemistry class, and after each overhaul, reset the boiler physical parameter.

Claims (2)

1. the furnace outlet gas temperature based on the gas energy balance is optimized measuring method, it is characterized in that, may further comprise the steps:

Step 1: the metal quality boiler furnace and the flue characteristic that comprise furnace volume, burner hearth heat interchanging area and heat interchanger heat interchanging areas at different levels are set, by the OPC communications protocol, set up the OPC client and send request of data to the opc server end that DCS carries, the OPC client is carried out real-time sampling and is obtained the boiler operatiopn data, data are carried out 5 smoothing processing, and described OPC client is the OPC client that Matlab carries;

Step 2: set up science computing platform and man-machine interactive platform the engineer station;

Step 3: burning exothermic equilibrium and water-cooling wall radiation heat transfer balance based on boiler furnace calculate furnace outlet gas temperature T1; Heat interchanger mainly is divided into superheater and reheater, based on exit gas energy, reheater energy equilibrium and the superheater energy equilibrium of boiler flue, utilizes flue gas physical parameter storehouse, calculates furnace outlet gas temperature T ₂

Step 4: according to the furnace outlet gas temperature T that calculates ₁With T ₂, the mode of employing linear superposition, i.e. T=a * T ₁+ b * T ₂Calculate final burner hearth cigarette temperature result, wherein coefficient a gets 0.3, and coefficient b gets 0.7;

Step 5: according to the variation correction boiler physical parameter that natural fuel characteristic, boiler furnace and flue characteristic, heat interchanger characteristic take place as time passes, carry out the parameter rolling and upgrade.

2. the furnace outlet gas temperature based on the gas energy balance according to claim 1 is optimized measuring method, it is characterized in that the time interval of described sampling is 5 seconds.

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